Theoretical studies on one-photon and two-photon absorption properties of a series of dibenzothiophene derivatives

The one-photon and two-photon absorption properties of a series of dibenzothiophene derivatives are investigated by use of the analytic response theory at DFT level. The numerical results show that these molecules have relatively strong two-photon absorption cross-sections. In the visible light region, the maximal one-photon absorption strengths of the molecules occur in the first excited state. (E,E)-1,4-Bis[3-vinyl-dibenzothiophene]-2,5-dimethoxybenzene molecule has the largest values for both one-photon absorption intensity and two-photon absorption cross-section among the studied molecules. Furthermore, it is shown that the maximal one-photon absorption intensity is monotonically increased as the electron-donating ability of donor group is enhanced. However, the two-photon absorption cross-section displays a non-monotonic increment. The charge-transfer process is analyzed when the molecule is excited from the ground state to charge-transfer state. A general agreement with experimental measurement is obtained.